There is a need to measure the purity of fluids in many different circumstances. Devices used for measuring fluid purity in general, and for identifying and quantifying the amount of impurities in particular, commonly use light as a probing mechanism. Such devices are generally referred to as photometers. A specific type of photometer is the spectrophotometer, which permits adjustment of the light frequency (i.e., wavelength), for making measurements at multiple frequencies. The term “spectrophotometer” as used herein includes any photometer, including reflectometers, transmissometers, and nephelometers, adapted for this purpose.
Light that is used to irradiate material may either be reflected by the material, transmitted through the material, or absorbed by the material. Where the light is absorbed by the material, the material may also emit light in response, or fluoresce. In devices used to measure purity, one of three basic measurement methodologies following from these potential interactions of the light with the matter is generally employed. These methodologies measure the parameters absorption, reflectance, and fluorescence and are referred to herein as absorption, reflectance, and fluorescence methodologies. According to the various methodologies, a light detector is disposed with respect to a light transmitter so that the detector is optimally positioned to be responsive to the associated parameter.
However, there has been a lack of measuring mechanisms that can measure light absorption of liquid samples in a precision manner.